000 AGXX40 KNHC 201804 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 204 PM EDT WED APR 20 2016 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS. ...GULF OF MEXICO... MODEL PREFERENCE: BLEND OF THE 00Z GFS WITH PREVIOUS OFFICIAL FOR WINDS THROUGH THU NIGHT THEN 00Z/20 ECMWF ADDED TO BLEND. OFFICIAL WAVE FORECAST BLENDED WITH 12Z NWPS. HIGH CONFIDENCE THROUGH THU THEN MEDIUM CONFIDENCE. WINDS ACROSS THE GULF OF MEXICO ARE EXPECTED TO REMAIN BELOW THE ADVISORY CRITERIA OF 20-25 KT ACROSS THE BASIN THROUGH SUN NIGHT...WITH THE MOST LIKELY SITE TO SEE WINDS APPROACH THIS CRITERIA LYING ALONG THE N AND NW COAST OF THE YUCATAN PENINSULA THIS EVENING AND THU EVENING. THE TYPICAL DIURNAL THERMAL TROUGH SET UP IS EXPECTED ALONG THE YUCATAN...CARRYING AN AREA OF ENHANCED WINDS NW ALONG WITH THE TROUGH DURING THE OVERNIGHT HOURS. THE GFS TYPICALLY HANDLES THIS SET UP BEST. BY FRI...THE 12Z GFS AND 00Z/20 ECMWF DIVERGE WITH THE TIMING OF THE COLD FRONT EXPECTED TO PASS THROUGH THE NORTHERN GULF THROUGH SAT. THE ECMWF IS FASTER THAN THE GFS. BOTH MODELS KEEP WINDS WELL BELOW ADVISORY CRITERIA. A BLEND OF THEIR FORECASTS SEEMS SUFFICIENT TO REDUCE THE TIMING DIFFERENCES. THERE IS GENERAL AGREEMENT ON HIGH PRES MIGRATING E THROUGH THE N GULF OVER THE WEEKEND. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: BLEND OF THE 00Z GFS WITH PREVIOUS OFFICIAL FOR WINDS THROUGH FRI THEN 00Z/20 ECMWF ADDED TO BLEND. OFFICIAL WAVE FORECAST BLENDED WITH 12Z NWPS THROUGH FRI THEN 00Z/20 EC WAVE ADDED IN THE TROPICAL ATLC. MEDIUM CONFIDENCE. THE PRES GRADIENT WILL REMAIN TIGHTEST ACROSS THE N CENTRAL CARIBBEAN THROUGH FRI...WITH WINDS AND SEAS EXPECTED TO MEET OR EXCEED THE ADVISORY CRITERIA OF 20-25 KT AND 8 FT...RESPECTIVELY...THROUGH FRI IN THE LEE OF CUBA...THE WINDWARD PASSAGE AND ITS APPROACHES...AND THE S COAST OF HISPANIOLA. BLENDING THE PREVIOUS OFFICIAL GRIDS WITH THE 12Z GFS BUMPED UP WINDS HERE COMPARED TO THE 12Z PRODUCT PACKAGE. STRONG HIGH PRES OVER THE SE UNITED STATES WILL REMAIN IN PLACE INTO THU BEFORE SHIFTING SE THROUGH THE BERMUDA FRI AND WEAKENING E OF THE AREA SAT AS NEW TROUGHING BEGINS TO BUILD IN THE FAR W PORTION OF THE SW N ATLC ZONE. WINDS WILL DIMINISH ACROSS THE N CENTRAL CARIBBEAN DURING THIS TIME. IN THE TROPICAL ATLC...A FEW ROUNDS OF NORTHERLY SWELL WILL KEEP SEAS GENERALLY IN THE 4-6 FT RANGE THROUGH THU NIGHT...WITH A STRONGER PUNCH OF NORTHERLY SWELL EXPECTED TO BRING SEAS TO NEAR 8 FT FRI NIGHT THROUGH THE WEEKEND. THE NORTHERN STREAM PATTERN FAVORS A BLEND OF THE 12Z GFS AND 00Z/19 ECMWF BY THIS POINT...AND THE EC WAVE GENERALLY HANDLES LONG-PERIOD SWELL IN THE OPEN ATLC WATERS BETTER THAN THE NWPS AND MWW3...SO IT WAS ADDED TO THE BLEND THU NIGHT ONWARD. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: BLEND OF THE 00Z GFS WITH PREVIOUS OFFICIAL FOR WINDS THROUGH FRI THEN 00Z/20 ECMWF ADDED TO BLEND. OFFICIAL WAVE FORECAST BLENDED WITH 12Z NWPS THROUGH FRI THEN 00Z/20 EC WAVE ADDED. MEDIUM CONFIDENCE. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH THE COLD FRONT SWEEPING THROUGH NE WATERS THROUGH THU...WITH WINDS EXPECTED TO DIMINISH BELOW 20-25 KT THERE AROUND 09Z. THE PRIMARY HIGH PRES OVER THE EASTERN GREAT LAKES EXTENDS A RIDGE SE THROUGH A SECOND HIGH CENTER NEAR 30N78W TO 26N68W. THE PRIMARY HIGH IS FORECAST TO SHIFT OFFSHORE LATE THU...WEAKEN AS IT MOVES THROUGH BERMUDA FRI AND CONTINUE TO WEAKEN AS IT PASSES SOUTHEASTWARD OVER THE WEEKEND. THE MODELS ARE IN REASONABLY GOOD AGREEMENT ON THIS SCENARIO...BUT DIFFER WITH THE TROUGHING EXPECTED TO BUILD OVER W WATERS FRI AND SAT. AS STATED IN THE GULF OF MEXICO SECTION...A BLEND OF THE 12Z GFS AND 00Z/20 ECMWF WAS PREFERRED WITH THE WEAK COLD FRONT MOVING ACROSS THE N GULF AND ENTERING NW WATERS IN THE SW N ATLC SOMETIME SAT. THE ECMWF CONTINUES TO BE FASTER THAN THE GFS. A BLEND SEEMS IN ORDER TO RESOLVE THE TIMING DIFFERENCES. A BLEND OF THE 12Z NWPS AND 00Z/20 EC WAVE IS ALSO PREFERRED FOR THE SEAS BY THU NIGHT...ESPECIALLY AS THE EC WAVE GENERALLY HANDLES LONG-PERIOD SWELL IN THE OPEN ATLC WATERS BETTER THAN THE NWPS AND MWW3. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANE WARNINGS.GOV/MARINE $$ .FORECASTER SCHAUER. NATIONAL HURRICANE CENTER.